Important step

But he says it is an important step in research because it does not require the use of embryos in creating the type of stem cell capable of transforming into any other type of cell in the body.

"A thorough examination of the stem cells derived through this technique demonstrated their ability to convert just like normal embryonic stem cells, into several different cell types, including nerve cells, liver cells and heart cells," says Mitalipov.

He says since the reprogrammed cells use genetic material from the patient, there is no concern about transplant rejection.

"While there is much work to be done in developing safe and effective stem cell treatments, we believe this is a significant step forward in developing the cells that could be used in regenerative medicine," Mitalipov says.

"This study is an important advance that will not only influence scientific thought but in fact could change future therapies," Vissel says.

"The point is we have a new way to ensure new cells being generated for treatment would be genetically identical to the person being treated, since they originated from that person in the first place.

"We may now be able to take a person's skin cells, use them to make embryonic stem cells, repair genetic problems, and then turn the embryonic stem cells into new nerve cells, for example, that repair the person's brain."

Ethical issues

While the new approach overcomes the immune rejection hurdle, Associate Professor Ernst Wolvetang of the Stem Cell Engineering Group at the Australian Institute for Bioengineering and Nanotechnology says the method still relies on the "willingness of women to undergo super-ovulation and donate [eggs] for such purposes, a procedure that carries both inherent risks and its own socio-ethical concerns".

"The paper is of academic interest but unlikely to have any bearing on the therapeutic use of stem cells," he says.

Stanley adds the ability to reprogram tissue-derived cells into embryonic stem cells is already being achieved using "other methods that are much more accessible and simpler".

Human clones concern

While some reports hailed the work as a first step in cloning humans, the researchers were quick to dampen such suggestions, saying their focus was on "therapeutic' uses.

The team pointed out years of research on monkey cells using the same technique have not successfully produced any monkey clones.

Since the human cells used in the study appeared even more fragile, they say it is unlikely clones can be made.

"While nuclear transfer breakthroughs often lead to a public discussion about the ethics of human cloning, this is not our focus, nor do we believe our findings might be used by others to advance the possibility of human reproductive cloning," the researchers say.

Scientists hope that stem cell research will offer new pathways in the fight against Parkinson's disease, multiple sclerosis, spinal cord injuries and blindness.